Electrical regulator



April 11, 1950 N. N. GEORGE ETAL smcmcn mum-on Filed Sept. 19, 1945 IN VEN TOR N145 M 650/765 fiflYrm/m v. KL INE @2 21 M fl TTO/TNEY Patented Apr. 11, 1950 UNITED STATES PATENT OFFICE ELECTRICAL asoum'roa Nils N. George and Raymond V. Kline, Minneapolis, Minn, asslgnors to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn a corporation of Delaware Application September 19, 1945, Serial No. 517,255

3 Claims. (Cl. 323-47) This invention relates to the held of electrical regulators, and more particularly to such regulators in which a factor, such for example as the voltage, of the electrical energization of a load circuit is maintained constant regardless of change in the magnitude of the load or variation in the source of electrical energy.

It is an object of this invention to provide a voltage regulator which is accurate and dependable, and which embodies no delicate moving parts.

It is a further object of our invention to provide such a regulator in which voltage is delivered to a load from a source through a control member which is so actuated that the voltage actually delivered to the load is maintained at a predetermined value regardless of change in the voltage of the source or in the magnitude of the load.

Various other objects, advantages, and features of novelty which characterize our invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and objects attained by its use, reference should be had to the subjoined drawing, which forms a further part hereof, and to the accompanying descriptive matter, in which we have illustrated and described a preferred embodiment of our invention. In the drawing,

Figure 1 is a schematic wiring diagram of a voltage regulator embodying our invention, and

Figure 2 is a fragmentary modification of Figure 1 showing the invention modified forregulating current rather than regulating voltage.

Referring now to Figure 1, it will be seen that alternating voltage from a source It is transmitted to a load ll through a controller I! mechanically actuated by a motor l3 whose energization in turn is controlled by a regulator l4 in such a fashion as to maintain the voltage supplied to load II at a constant value regardless of variations in the voltage of source It and in the load ll. Regulator i4 is energized from com troller i2, and in the regulator a rectifier l5 energized through a transformer l6 supplies half wave voltage to a pair of filters l1 and 20. A fixed portion of the output voltage of one of the filters is electronically regulated, and compared with an unregulated, adjustable portion of the output of the other filter. Voltages proportional to the output voltages of the filters appear as voltage drops across the input resistors of a grid controlled rectifier stage generally indicated at 2i, whose plates are energized from transformer fler stage appears as a voltage impressed upon the input of a discriminator stage 22 whose plate circuit is also energized from the output of controller I2 and which controls the energization of motor I! to adjust the voltage output from controller I! in accordance with the magnitude and sense of the unbalance.

Proceeding now to a detailed consideration of the circuit elements and connections going to make. up our invention, element it may be any suitable source of alternating voltage of the desired frequency and phase: the time-phase relationship of this voltage serves as a basis for comparison in determining questions of phase throughout the circuit, and an indication of phase relations in the circuit is given by signs indicating points of the same instantaneous polarity. Member It may be an alternator, a transformer, an inverter, or the conventional outlet for commercially distributed alternating current. In a preferred embodiment of our invention, source Ill comprises a 400 cycle inverter energized, as is customary in aircraft applications, from the storagefratteries and direct current generator of the era Controller I2 is shown as a variable auto-transformer having an input terminal 23, an output terminal 24, and a common terminal 25. The

transformer comprises a core 26 carrying a winding 21 which is provided with a fixed tap 30 and a movable slider 3i. One end of winding 21 is connected to terminal 25, tap ll! is connected to terminal 23, and slider ii is connected to terminal 24, all as shown. Devices of this nature are well known, one familiar form being supplied by the General Radio Company under the trade name Variac." The input of controller i2 is energized from source I 0 through conductor 32, and thrgugh conductor 3!, switch 34, and conductor 5.

Load Ii may be any type of inductive or noninductive load such as lighting units, electroplating tanks, and so forth, and is shown as having input terminals 35 and 31. In the preferred embodiment of our invention referred to, load H comprises electronic control equipment for the craft. Input terminal 36 of load Ii is connected to terminal 25 of control device I! by conductor 40. Input terminal 31 of load II is connected to output terminal 24 of control device I 2 by conductor 4|.

Motor I3 is shown as a capacitor motor having a rotor 42 and a pair of field windings 43 and 44. A capacitor 45 is connected in parallel it. Any unbalance in the grid controlled rectiwith field windin 44, and the parallel combination is connected to a first pair of output terminals 46 and 41 for the motor. Field winding 43 is connected to a second pair of terminals 50 and 5|, in series with a capacitor 52. The terminals 50 and Ill are, in turn, connected by conductors 54, 55, 56, and 51 to terminals 24 and 25 or transformer I2. 3

The current in coil 43 leads the output voltage of transformer I2, which is impressed across the series circuit, by 90 degrees. If current in phase with the output voltage of transformer I2, flows in coil 44, motor I3 operates in a first direction, while if the current in coil 44 is of the opposite phase, the motor operates in the opposite direction, as is well known to those skilled in the art. 7

Rotor 42 is connected to actuate adjustable tap 3| of control device I2 by a suitable con necting means 53, which may include a gear reduction train if desired. Operation of motor l3 in the first or forward direction is effective to increase the output voltage of transformer I2, while the operation of the motor in the reverse direction decreases the output voltage of the transformer.

From the foregoing, it follows that energization of load II from source I is controlledby the position of sliding contact 3| of control member I2, and that the position of the sliding member is in turn controlled by operation of motor I3. The means whereby operation of motor I3 is controlled is comprised in regulating circuit I4 which will now be described.

Regulator I4 is provided with a pair of input terminals 60 and 6|, energized from terminals Hand 25 of control device I2 through conductors 56 and 62 and conductors 54 and 63. Regulator I4 is also provided with a pair of output terminals 64 and 65, which are connected to terminals 46 and 41 of motor I3 by conductors.

66 and 69.

Transformer I6 is shown to comprise a core 13 carrying a primary winding 66 and a pair of secondary windings 61 and 10 having center taps H and 12, respectively. Primary winding 66 is energized from input terminals 60 and GI by conductors 14 and 15 and conductors 15 and 11. The transformer is so connected that when terminal 23 of transformer I2 is positive with respect ,to terminal 25 the lower terminal of winding 10 is positive with respect to the upper terminal, instantaneous polarities being indicated in the drawing.

Rectifier I is shown to comprise a pair of diodes 80 and III contained in a common envelope -02. Diode 00 comprises a cathode 83 and an anode 84: diode 8| similarly comprises a cathode 85 and an anode 86. Anodes 84 and 86 are energized in 180 phase relation from the end terminals of secondary winding 61 of transformer I6 by conductors 81 and 90. Cathodes 83 and 65 are joined within the tube, and are heated indirectly by suitable filament heaters which are Filter I1 is shown to comprise a'resistor 94 and a-capacitor 95 connected in series across the 9I through conductors 96 and I06, resistor I04,

conductors I01 and H0, capacitor I05, and conductor III to conductor 92. a

A voltage divider H4 is connected across the output of filter I1, and is shown to comprise a resistor H5 and voltage regulator I8 which in turn comprises a pair of voltage regulator tubes I I6 and H1. Due to the well known action of the regulator tubes, a constant voltage is maintained between conductor 92 and the common terminal of regulator I8 and resistor II4: to the common terminal referred to is connected a conductor I20, which is positive with respect to conductor 92.

Across the output of filter 20 is connected 1 second voltage divider I 2I shown to comprise a fixed resistor I22 and a variable resistor I23 having a resistance winding I24 and a contacting slider I25. The voltage drop across this second voltage divider, between slider I 25 and conductor 92, diifers from that across the first voltage divider in that while the latter remains constant for changes in the output of its filter, the former voltage varies as the output of its filter varies. Of this variable voltage, any desired portion, within the limits of adjustability of variable resistor I23, may be taken off, the magnitude of the portion being determined by the position of slider I25. A conductor I26, connected to slider I25 as shown, is positive with respect to conductor 92.

Rectifier stage 2I' comprises a pair of grid controlled rectifiers I30 and I3I which are shown as enclosed in a common envelope I32. Rectifier I39 comprises an anode I33, a grid I 34, and a cathode I 35. Rectifier I 3| comprises an anode I36, a grid I31, and a cathode I40. Cathodes I35 and I40 are indirectly heated by filament heaters which are not shown, and are joined within the tube. Grid I34 is maintained at the potential of conductor I26 by conductor MI, and grid I31 is similarly maintained at the potential of the conductor I20 by conductor I42. Cathodes I35 and I40 are grounded through conductors I43, I44, I45, and I46. A pair of resistors I41 and I50 are connected to serve as the conventional input resistors for the rectifiers. Conductor 92 is grounded through condenser I5I and conductors I45 and I46.

The anodes of the grid controlled rectifiers are energized from secondary winding 10 of transformer I6 through suitable dropping resistors I52 and I53. The anode circuit for rectifier I30 may be traced from the upper'terminal of Winding 10 through conductor I54, resistor I52, conductor I55, anode I 33,=cathode I 35, and conductors I43, I44, and I45, and I56 to center tap 12 of the transformer winding. Similarly, the anode circuit of rectifier I 3| may be traced from the lower terminal of secondary winding 10 through conductor I51, resistor I53, conductor I58, anode I36, cathode I40, and conductors I43, I44, I45, and I56 to the center tap' of the transformer winding. From this arrangement it will be evi dent that the two rectifier anodes are energized in degree phase relationship.

Discriminator stage 22 is shown to comprise a pair of electron discharge devices I" and I52, an input resistor I53, and an energizing transformer I. Although triodes function with perfect satisfaction in this circuit, I have found it convenient in the preferred embodiment of our invention to make use of tetrodes. connecting what is normally the screen grid in each tube to its anode to comprise the effective anode of the tube. Thus, electron discharge device II comprises an anode I55, a screen grid I connected thereto, a control grid I51, and a cathode Ill, and electron discharge device I52 comprises an anode III, a screen grid I12 connected thereto, a control grid Ill, and a cathode I'll.

It will be observed that the cathodes are connected to a common conductor I I5 which in turn is grounded through conductors I15, I18 and I46. One end of input resistor I5! is similarly grounded through conductors I11, I15, and I45.

The grids of tetrodes lil and I52 are joined by conductors I" and III and connected to the ungrounded end of resistor It! by conductor I82. A pair of resistors I93 and I 54 are connected in series between anode I" of triode Ill and anode Iii of triode Ill, and between the common terminal I55 of these two resistors and the grid conductor I82 of the discriminator stage is connected a suitable coupling capacitor I55.

Transformer I is shown to comprise a core I86 carrying a primary winding Ill and a secondary winding I having a center tap I55. Primary winding I is energized from input terminals and 6| of regulator ll through conductors II and Ill and conductors I6 and Ill. The effective anodes of tetrodes I5I and I 52 are energized from secondary winding I through conductors I! and I 92, respectively. Center tap I85 of secondary winding I is connected to output terminal of regulator II by conductor I91, while output terminal 55 of regulator Il is grounded through conductors 2", I15, and I". The input to discriminator stage 22 may thus be said to comprise a normally balanced network energized in secondary winding II and comprising resistors I52 and I51 in parallel with the plateresistances of triodes I30 and I II, the latter being determined by the voltages in the grids of the triodes.

Operation The operation of our invention will now be setforth. Upon closin switch 34, the voltage derived from source III is impressed upon transform'er I2, and by transformer action a voltage appears between slider SI and fixed terminal 25 of the transformer and is transmitted to load II through conductors 40 and U. As will readily be apparent to those skilled in the art, the voltage made available to load II is related to the voltage impressed on the input of the transformer in the same fashion as is the number of turns between terminals 23 and 25 to the number of turns between slider SI and terminal 25. That is to say, when slider ll is above tap 25in the drawing, the voltage supplied to load II is greater than that supplied from source II, while when the slider is below the tap, the voltage supplied to the load is less than the voltage derived from the source.

Transformer I2 not only energizes load II, but also provides energy for regulator II and for one winding of motor I3. The voltage between slider 3| and terminal 25 is in phase with the voltage between tap 23 and terminal 25 and the following voltages are of the same phase; the voltage cordingly a variable between terminals II and 50 of winding ll of motor I3, the voltage between the lower and upper terminals of primary winding 55, and the voltage between the left and right terminals of primary winding I03. The voltage between terminals "and 35 of load II is also of the same phase although ordinarily the nature of load II is such that this phase relation is not of significance.

The current through winding 43 also flows through capacitor 52, and the electrical characteristics of the winding and the capacitor are so chosen that the combination is series resonant for energization at the frequency of source II. The current flowing through the series circuit is therefore in phase with the voltage between terminals 5!! and SI, and since the voltage drop acros winding 43 lags the current through the winding b the voltage drop across the field winding also lags the standard voltage by 90. Field winding 43 is continuously energized as is shown in the diagram and any change in the voltage output from transformer I2 is transmittedtoiield winding 43 justas itistoload II and regulator II.

Primary winding 56 of transformer I6 is energized from the output of transformer l2, and the amplitude of the voltage made available by transformer action in secondary winding 51 varies with change in the output of transformer I2. By the familiar full-wave rectification process, a voltage is derived from rectifier I5 which is unidirectional in nature and variable in magnitude according to the well known full wave outline.

This voltage also varies with variation in the voltage supplied to primary winding 55, and acpulsating voltage is supplied the pulsations in this voltage, however, are first considerably smoothed out by the action of capacitor 93. Filter I! still further smooths out the wave form, and a substantially constant unidirectional voltage is impressed across voltage divider II 4. The magnitude of the voltage impressed across divider Ill varies with change in the amplitude of the voltage energizing transformer primary 65, but due to the familiar action of the voltage regulator tubes shown at It the voltage between conductor I2. and conductor 92 remains constant for variation within certain practical limits of the energization of the primary winding of the transformer.

The same voltage that is supplied to filter .I I is also supplied to filter 20, and the output of filter 2| is impressed across the voltage divider including resistors I22 and I24. Of this voltage, any desired portion determined by the position of slider I25 appears between the slider and conductor 52, but the magnitude of this voltage varies with the amplitude of the voltage energizing of primary winding 56, rather than being constant, as is the voltage between conductors I20 and 92.

It will be apparent that for any particular setting of slider I25 there is a particular value of voltage applied to primary winding 66 which brings about a condition of equality between the outputs of the two voltage dividers referred to. The further downwardly along winding I24 slider I25 is displaced, the greater is the voltage that is required to be applied to transformer to in sure that the voltage between conductor 92 and slider I25 has the desired equivalent value. Similarly, the further upward slider I25 is displaced along winding I24, the smaller is the voltage appliedtoprimarywindingiithatisrequiredto bring about the desired condition of equivalents. It will, of course, be understood that there are certain limits to the ability of regulator I8 to maintain a constant voltage output regardless of the input energization of the voltage divider, and any system involving our invention must be so designed as to operate within these limits.

When the condition of voltage equivalence has been attained, slider I25 is at the same potential with respect. to conductor 92 as is conductor I20, and since grids I34 and I3! are connected thereto, the grids are at the same potential compared with conductor 92. By the use of equal resistors I41 and I50, the potential of cathodes I35 and I40 is maintained half way between that of grid I34 and grid I31 whenever a potential diflerence appears between the two grids. In this respect, the potential of the cathodes differs from the potential of conductor 92, since it is only at the condition of balance that the voltage drop across the regulator tubes is equal to the voltage drop between slider I25 and conductor 92.

Due to capacity coupling between secondary winding 10 and secondary winding 61, the entire rectifler-filter circuit, and thus the grids of the triodes, would be free to float at some potential with respect to the cathode which would be determined by the magnitude of the capacity coupling. To avoid this, conductor 92 is connected with conductor I45 through capacitor I5I, which accordingly cooperates with capacitors I05 and 95 to shunt around the grids any alternating potentials with respect to ground which are transmitted due to capacity coupling in the transformer.

The anodes I33 and I35 of triodes I30 and I3I are energized in 180 phase relationship from winding of transformer 66. So long as the voltage output of transformer I2 is maintained at the desired value, the voltage drop across the regulator I8 is equal to that between slider I25 and conductor 92, and the grids I34 and I31 are at the same potential. Then for a particular half cycle of source I0 when plate I33 of triode I30 is negative, the voltage between the plate and the cathode follows the output of the upper half of secondary winding 13 in magnitude. During this half cycle the voltage between the plate and cathode of triode I3I is of the opposit polarity, however, and plate current flows in the anode circuit of the triode, thus reducing the plate-to-cathode voltage by the voltage drop in the plate resistance so that it does not follow the voltage outline of the lower half of secondary winding 10. The voltage relations of the two triodes are reversed in the ensuing half cycle of the source, and equal plate currents result in sequential equal voltage drops in the two equal plate resistors. The tube voltages are added in opposition by resistors I93 and I94 in conventional full-wave rectifier position, and the resulting voltage impressed on the input of discriminator stage 22 has a principal component whose frequency is twice that of the source, and no component having the frequency of the source.

If the voltage drop between conductors I and 92 is not equal to that between conductors I26 and 92, grids I34 and I31 are no longer at the same potential, one being above and the other being below the cathode potential which is maintained midway between the grid potentials by resistors H3 and I44. The voltage drops in the plate resulting from adding the two voltages now has a component of the frequency of the source. This component is in phase with the source if the voltage supplied to the load is too low and out of phase if the voltage is too high.

Plates I65 and HI oi discriminator stage 22 are energized in 180 degrees phase relation from secondary winding I84 01' transformer I64. If the voltage just described is in phase with the source,

the grid and plate voltages of.triode I6I are in phase, and this triode discharges during first alternate half cycles of the source: the discharge circuit starting from the right hand terminal of winding I84 and including conductor I9I, plate I65, cathode 10, junction point I15, conductors I19 and 200, terminal 64, conductor 68, terminal 46, condenser and winding 44 of motor I3, terminal 41,'conductor 69, terminal and conductor I91 to center tap I85. If the voltage is out of phase with the source, the grid and plate voltages of triode I62 are in phase, and this triode discharges during second alternate half cycles of the source:' the discharge circuit starting from the left hand terminal of winding I84 and including conductor I92, plate I1I, cathode I14, junction point I15, conductors I19 and 200, terminal 64, conductor 46, condenser 45 and winding 44 of motor I3, terminal 41, conductor 69, terminal 65, and conductor I91 to center tap I85. Discharge of triode I6I is effective to energize winding 44 of motor I3 with voltage having a component in phase with the source, causing this motor to operate in a forward direction to increase the voltage output of the transformer. Discharge of triode I62 is effective to energize winding 44 of motor I3 with voltage having a component out of phase with the source, causing the motor to operate in a reverse direction to decrease the voltage output of the transformer.

Since the plates of the discriminator tubes are energized at the frequency of the source. the eifect of a voltage of double the frequency is equal upon both the discriminator tubes and results in no effective energization of the motor.

In brief, increase of the voltage delivered to the load above a predetermined value, which is set by adjustment of slider I25, causes the unregulated voltage of filter 20 to exceed the regulated voltage of filter I8, causing the potential of grid I34 to exceed that of grid I31. A voltage out of phase with the source is impressed upon the grids of the discriminator tubes, actuating motor I3 to operate in the reverse direction, adjusting transformer I2 to decrease its output voltage. Decrease of the voltage delivered to the load below its predetermined level causes opposite actuation of the system.

In Figure 2 is shown a fragmentary view of the circuit of Figure 1 modified so that the system is responsive to changes in current rather than changes in voltage. A resistor 300 is connected in series with the load, and the voltage drop across this resistor actuates the system just as described above.

Numerous objects and advantages of my invention have been set forth in the foregoing description, together with details of the structure and function of the invention, and the novel features thereof are pointed out in the appended claims. The disclosure, however, is illustrative only, and we may make changes in detail, especially in matter of shape, size and arrangement of parts, within the principle of the invention, to

sistors are no longer equal, and the voltage rere the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

We claim as our invention:

1. In a device of the class described, in combination: a source of alternating voltage; an electric load circuit; a control circuit; a variable autotransformer supplying to said circuits a controlled voltage derived from said source; a split phase motor actuating said autotransformer to vary the amplitude of said controlled voltage; means energizing one of the field windings of said motor from the load side of said autotransiormer; and means, independent of said load circuit, energizing the other field winding of said motor in accordance with deviation of the voltage supplied by said autotransformer from a predetermined value; said last named means includin a pair of rectiflers; transformer means energizing said rectifiers, in 180 degree phase relationship, with voltage supplied by said autotransformer; a complex electrical network connected to said rectificrs and including means regulating a portion of the output of said rectifiers to comprise Voltage comparison means; a pair of grid controlled rectifiers; means connecting said complex electrical network to said grid controlled rectifiers; means energizing said grid controlled rectifiers from said transformer; an electronic phase discriminator stage; means energizing said discriminator stage from said autotransformer; means connecting the outputs of said grid controlled rectifiers in opposition to comprise an input signal for said discriminator stage; and means continuously energizing the second field winding of said motor from the output of said discriminator stage.

2. In combination, a source of power, said source being subject to voltage variation, rectii'ying means having input and output terminals, transformer means energized from said source of power, means connecting said transformer to the input terminals of said rectifying means, a voltage comparison network having voltage input and output terminals, said output terminals having a voltage thereon subject to reversal in polarity upon a change in magnitude of the voltage on said input terminals, means connecting the output terminals of said rectifying means to the input terminals of said comparison means, a pair ternate half cycles of said source of power, means connecting the output terminals of said voltage comparison network to the control electrodes of said last named rectiflers to variably bias said rectifiers in accordance with the voltage on the output terminals of said comparison network, alternating current output coupling means common to the anode circuits of said last named rectifiers, and alternating current driven electronic ampli fying and discriminating means biased by said coupling means, said amplifying mean having an output whose frequency is the same as said source of power and whose phase is dependent upon the variations in voltage of said source of power.

3. In combination, adjustable voltage control means having input and output terminals, electronic detecting means continuously energized by said control means and variably responding to the voltage on the output terminals of said control means, said electronic detecting means comprising a first pair of opposed amplifier tubes and a second pair of opposed amplifier tubes, an alternating current source of supply voltage on the output terminals of said control means and comprising center tapped transformer windings, means connecting said opposed amplifiers to be oppositely energized by said windings, motor means having a pair of energizing windings, means connecting one of said pair of windings of said motor means directly to the output terminals of said control means, means connecting the other pair of windings of said motor means continuously to said second pair of opposed amplifier tubes for variable energization in accordance with the response of said detecting means to the voltage of said control means, and coupling means connecting said motor means to said control means.

NILS N. GEORGE. RAYMOND V. KLINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,239,768 Artzt Apr. 29, 1941 2,302,889 Reed Nov. 24, 1942 2,343,116 Ryder et al Feb. 29, 1944 2,368,582 Sziklai Jan. 30, 1945 2,423,540 Wills July 8, 194'! 

